GPS技术在上海市地面沉降研究中的应用

上海市自1998年开始开展了利用GPS技术监测地面沉降的研究，先后进行了可行性论证、GPS基准网建设、数据处理和平差方法的探索等一系列课题的研究，并布设了由34点组成的覆盖整个上海市的地面沉降监测基准网.为了进一步提高基准网的监测精度和沉降监测的时空分辨率，于2004年又布设了4个24小时连续运行的GPS固定站，对上海市地面沉降实施连续监测.为了考查GPS沉降监测的大地高可能达到的精度，研究合理的观测纲要与数据处理方案，本文在介绍并总结了上海市地面沉降GPS监测工作的同时，分析了GPS沉降监测基准网前后6期的观测数据.数据分析采用GAMIT/GLOBK软件包和GPS_NET软件，计算结果表明，在基线边长达到30～40km时，GPS在大地高方向上的中误差仍可控制在2mm左右，由此推算GPS监测地面沉降的分辨率在3mm左右，完全能够满足上海市地面沉降监测的需要.

The application of GPS in shanghai land subsidence research

Shanghai launched the research of monitoring the land subsidence with GPS since 1998,which includes the demonstration of monitoring land subsidence with GPS,the construction of GPS fiducial network,GPS Data processing and network adjustment etc.Also,the GPS fiducial network making up of 34 sites which almost cover the whole shanghai region was constructed.On the other hand,to improve the precision of the GPS fiducial network and the spatio-temporal resolution of Shanghai land subsidence monitoring,four GPS Continuously Operating Reference Stations(CORS) have been constructed on 2004.Here,based on the work accomplished,we introduce and summarize the experience obtained.What's more,to examine what precision of ellipsoid height can be achieved,get the reasonable observation program and the best scheme of GPS Data processing,we analyzed six groups of GPS data observed since 1998 with software GAMIT/GLOBK and GPS_NET.Results indicate that the precision of WGS-84 ellipsoid height can be best as 2mm even the baseline's length is up to 30~40km.This order of precision can be used to separate the subsidence more than 3mm,which can perfectly meet the need of Shanghai land subsidence monitoring.